[{"id":33502,"web_url":"https://patchwork.libcamera.org/comment/33502/","msgid":"","date":"2025-02-27T21:00:49","subject":"Re: [PATCH] ipa: libipa: Fix bug in ExposureModeHelper that leads to\n\toscillations in AEGC","submitter":{"id":156,"url":"https://patchwork.libcamera.org/api/people/156/","name":"Dan Scally","email":"dan.scally@ideasonboard.com"},"content":"Hi Stefan\n\nOn 27/02/2025 19:58, Stefan Klug wrote:\n> The ExposureModeHelper::splitExposures() runs through the configured\n> stages to find the best gain/exposure time pair. It first raises the\n> exposure time until it reaches the limit of the current stage. Then it\n> raises the gain until that also reaches the limit of the current stage.\n> After that it continues with the next stage until a match is found.\n>\n> Due to a slight mistake in the initial code, the second step doesn't\n> work as expected because the exposure time gets divided by the gain of\n> the current stage, effectively leading to a jump of the gain value from\n> the maximum gain of the last stage to the maximum gain of the current\n> stage instead of gradually increasing the gain value.\n>\n> Depending on the tuning file this leads to very visible oscillations and\n> jumps in the brightness.\n>\n> Fix by clamping the exposure time in the second step to the maximum\n> exposure time of the current stage.\nGreat catch!\n> While at it, add two comments for easier understanding.\n\n\nHonestly those two make the whole thing so much clearer...and so does directly specifying \nstageExposureTime.\n\n\nReviewed-by: Daniel Scally \n\n>\n> Fixes: 34c9ab62827b (\"ipa: libipa: Add ExposureModeHelper\")\n> Signed-off-by: Stefan Klug \n> ---\n> src/ipa/libipa/exposure_mode_helper.cpp | 4 +++-\n> 1 file changed, 3 insertions(+), 1 deletion(-)\n>\n> diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp\n> index f235316d3539..0c1e99e31a47 100644\n> --- a/src/ipa/libipa/exposure_mode_helper.cpp\n> +++ b/src/ipa/libipa/exposure_mode_helper.cpp\n> @@ -182,6 +182,7 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const\n> \t\t * the stage limits are initialised.\n> \t\t */\n> \n> +\t\t/* Clamp the gain to lastStageGain and regulate exposureTime. */\n> \t\tif (stageExposureTime * lastStageGain >= exposure) {\n> \t\t\texposureTime = clampExposureTime(exposure / clampGain(lastStageGain));\n> \t\t\tgain = clampGain(exposure / exposureTime);\n> @@ -189,8 +190,9 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const\n> \t\t\treturn { exposureTime, gain, exposure / (exposureTime * gain) };\n> \t\t}\n> \n> +\t\t/* Clamp the exposureTime to stageExposureTime and regulate gain. */\n> \t\tif (stageExposureTime * stageGain >= exposure) {\n> -\t\t\texposureTime = clampExposureTime(exposure / clampGain(stageGain));\n> +\t\t\texposureTime = clampExposureTime(stageExposureTime);\n> \t\t\tgain = clampGain(exposure / exposureTime);\n> \n> \t\t\treturn { exposureTime, gain, exposure / (exposureTime * gain) };","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 988EDBE080\n\tfor ;\n\tThu, 27 Feb 2025 21:00:55 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 8CC2F6875E;\n\tThu, 27 Feb 2025 22:00:54 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id C573660322\n\tfor ;\n\tThu, 27 Feb 2025 22:00:52 +0100 (CET)","from [192.168.0.43]\n\t(cpc141996-chfd3-2-0-cust928.12-3.cable.virginm.net [86.13.91.161])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id E7C1F7F5\n\tfor ;\n\tThu, 27 Feb 2025 21:59:23 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"TmgLhpTv\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1740689964;\n\tbh=kqp7FJ43xILCN3tLpjZqc62MUrL+gXipxOeJx7LDD/4=;\n\th=Date:Subject:To:References:From:In-Reply-To:From;\n\tb=TmgLhpTv9wTE5FIMOTjNlHlb/iFxYrr75JbMIxgWjvqBabj5IqShLOSxXxEYOJrcf\n\tncImwRuWk90oB9uquAXdsb1+dHHoFnqYzIDBaDxUT16L/YPDHp4Eg5symUIYC2PMUy\n\tIGV55bEGXuRbQ3/mLVCTTZTjN84jmdWAYDYfcspE=","Message-ID":"","Date":"Thu, 27 Feb 2025 21:00:49 +0000","MIME-Version":"1.0","User-Agent":"Mozilla Thunderbird","Subject":"Re: [PATCH] ipa: libipa: Fix bug in ExposureModeHelper that leads to\n\toscillations in AEGC","To":"libcamera-devel@lists.libcamera.org","References":"<20250227195821.3172905-1-stefan.klug@ideasonboard.com>","Content-Language":"en-US","From":"Dan Scally ","Autocrypt":"addr=dan.scally@ideasonboard.com; keydata=\n\txsFNBGLydlEBEADa5O2s0AbUguprfvXOQun/0a8y2Vk6BqkQALgeD6KnXSWwaoCULp18etYW\n\tB31bfgrdphXQ5kUQibB0ADK8DERB4wrzrUb5CMxLBFE7mQty+v5NsP0OFNK9XTaAOcmD+Ove\n\teIjYvqurAaro91jrRVrS1gBRxIFqyPgNvwwL+alMZhn3/2jU2uvBmuRrgnc/e9cHKiuT3Dtq\n\tMHGPKL2m+plk+7tjMoQFfexoQ1JKugHAjxAhJfrkXh6uS6rc01bYCyo7ybzg53m1HLFJdNGX\n\tsUKR+dQpBs3SY4s66tc1sREJqdYyTsSZf80HjIeJjU/hRunRo4NjRIJwhvnK1GyjOvvuCKVU\n\tRWpY8dNjNu5OeAfdrlvFJOxIE9M8JuYCQTMULqd1NuzbpFMjc9524U3Cngs589T7qUMPb1H1\n\tNTA81LmtJ6Y+IV5/kiTUANflpzBwhu18Ok7kGyCq2a2jsOcVmk8gZNs04gyjuj8JziYwwLbf\n\tvzABwpFVcS8aR+nHIZV1HtOzyw8CsL8OySc3K9y+Y0NRpziMRvutrppzgyMb9V+N31mK9Mxl\n\t1YkgaTl4ciNWpdfUe0yxH03OCuHi3922qhPLF4XX5LN+NaVw5Xz2o3eeWklXdouxwV7QlN33\n\tu4+u2FWzKxDqO6WLQGjxPE0mVB4Gh5Pa1Vb0ct9Ctg0qElvtGQARAQABzShEYW4gU2NhbGx5\n\tIDxkYW4uc2NhbGx5QGlkZWFzb25ib2FyZC5jb20+wsGNBBMBCAA3FiEEsdtt8OWP7+8SNfQe\n\tkiQuh/L+GMQFAmLydlIFCQWjmoACGwMECwkIBwUVCAkKCwUWAgMBAAAKCRCSJC6H8v4YxDI2\n\tEAC2Gz0iyaXJkPInyshrREEWbo0CA6v5KKf3I/HlMPqkZ48bmGoYm4mEQGFWZJAT3K4ir8bg\n\tcEfs9V54gpbrZvdwS4abXbUK4WjKwEs8HK3XJv1WXUN2bsz5oEJWZUImh9gD3naiLLI9QMMm\n\tw/aZkT+NbN5/2KvChRWhdcha7+2Te4foOY66nIM+pw2FZM6zIkInLLUik2zXOhaZtqdeJZQi\n\tHSPU9xu7TRYN4cvdZAnSpG7gQqmLm5/uGZN1/sB3kHTustQtSXKMaIcD/DMNI3JN/t+RJVS7\n\tc0Jh/ThzTmhHyhxx3DRnDIy7kwMI4CFvmhkVC2uNs9kWsj1DuX5kt8513mvfw2OcX9UnNKmZ\n\tnhNCuF6DxVrL8wjOPuIpiEj3V+K7DFF1Cxw1/yrLs8dYdYh8T8vCY2CHBMsqpESROnTazboh\n\tAiQ2xMN1cyXtX11Qwqm5U3sykpLbx2BcmUUUEAKNsM//Zn81QXKG8vOx0ZdMfnzsCaCzt8f6\n\t9dcDBBI3tJ0BI9ByiocqUoL6759LM8qm18x3FYlxvuOs4wSGPfRVaA4yh0pgI+ModVC2Pu3y\n\tejE/IxeatGqJHh6Y+iJzskdi27uFkRixl7YJZvPJAbEn7kzSi98u/5ReEA8Qhc8KO/B7wprj\n\txjNMZNYd0Eth8+WkixHYj752NT5qshKJXcyUU87BTQRi8nZSARAAx0BJayh1Fhwbf4zoY56x\n\txHEpT6DwdTAYAetd3yiKClLVJadYxOpuqyWa1bdfQWPb+h4MeXbWw/53PBgn7gI2EA7ebIRC\n\tPJJhAIkeym7hHZoxqDQTGDJjxFEL11qF+U3rhWiL2Zt0Pl+zFq0eWYYVNiXjsIS4FI2+4m16\n\ttPbDWZFJnSZ828VGtRDQdhXfx3zyVX21lVx1bX4/OZvIET7sVUufkE4hrbqrrufre7wsjD1t\n\t8MQKSapVrr1RltpzPpScdoxknOSBRwOvpp57pJJe5A0L7+WxJ+vQoQXj0j+5tmIWOAV1qBQp\n\thyoyUk9JpPfntk2EKnZHWaApFp5TcL6c5LhUvV7F6XwOjGPuGlZQCWXee9dr7zym8iR3irWT\n\t+49bIh5PMlqSLXJDYbuyFQHFxoiNdVvvf7etvGfqFYVMPVjipqfEQ38ST2nkzx+KBICz7uwj\n\tJwLBdTXzGFKHQNckGMl7F5QdO/35An/QcxBnHVMXqaSd12tkJmoRVWduwuuoFfkTY5mUV3uX\n\txGj3iVCK4V+ezOYA7c2YolfRCNMTza6vcK/P4tDjjsyBBZrCCzhBvd4VVsnnlZhVaIxoky4K\n\taL+AP+zcQrUZmXmgZjXOLryGnsaeoVrIFyrU6ly90s1y3KLoPsDaTBMtnOdwxPmo1xisH8oL\n\ta/VRgpFBfojLPxMAEQEAAcLBfAQYAQgAJhYhBLHbbfDlj+/vEjX0HpIkLofy/hjEBQJi8nZT\n\tBQkFo5qAAhsMAAoJEJIkLofy/hjEXPcQAMIPNqiWiz/HKu9W4QIf1OMUpKn3YkVIj3p3gvfM\n\tRes4fGX94Ji599uLNrPoxKyaytC4R6BTxVriTJjWK8mbo9jZIRM4vkwkZZ2bu98EweSucxbp\n\tvjESsvMXGgxniqV/RQ/3T7LABYRoIUutARYq58p5HwSP0frF0fdFHYdTa2g7MYZl1ur2JzOC\n\tFHRpGadlNzKDE3fEdoMobxHB3Lm6FDml5GyBAA8+dQYVI0oDwJ3gpZPZ0J5Vx9RbqXe8RDuR\n\tdu90hvCJkq7/tzSQ0GeD3BwXb9/R/A4dVXhaDd91Q1qQXidI+2jwhx8iqiYxbT+DoAUkQRQy\n\txBtoCM1CxH7u45URUgD//fxYr3D4B1SlonA6vdaEdHZOGwECnDpTxecENMbz/Bx7qfrmd901\n\tD+N9SjIwrbVhhSyUXYnSUb8F+9g2RDY42Sk7GcYxIeON4VzKqWM7hpkXZ47pkK0YodO+dRKM\n\tyMcoUWrTK0Uz6UzUGKoJVbxmSW/EJLEGoI5p3NWxWtScEVv8mO49gqQdrRIOheZycDmHnItt\n\t9Qjv00uFhEwv2YfiyGk6iGF2W40s2pH2t6oeuGgmiZ7g6d0MEK8Ql/4zPItvr1c1rpwpXUC1\n\tu1kQWgtnNjFHX3KiYdqjcZeRBiry1X0zY+4Y24wUU0KsEewJwjhmCKAsju1RpdlPg2kC","In-Reply-To":"<20250227195821.3172905-1-stefan.klug@ideasonboard.com>","Content-Type":"text/plain; charset=UTF-8; format=flowed","Content-Transfer-Encoding":"7bit","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":33505,"web_url":"https://patchwork.libcamera.org/comment/33505/","msgid":"","date":"2025-02-28T04:24:13","subject":"Re: [PATCH] ipa: libipa: Fix bug in ExposureModeHelper that leads to\n\toscillations in AEGC","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"content":"On Thu, Feb 27, 2025 at 08:58:10PM +0100, Stefan Klug wrote:\n> The ExposureModeHelper::splitExposures() runs through the configured\n> stages to find the best gain/exposure time pair. It first raises the\n> exposure time until it reaches the limit of the current stage. Then it\n> raises the gain until that also reaches the limit of the current stage.\n> After that it continues with the next stage until a match is found.\n> \n> Due to a slight mistake in the initial code, the second step doesn't\n> work as expected because the exposure time gets divided by the gain of\n> the current stage, effectively leading to a jump of the gain value from\n> the maximum gain of the last stage to the maximum gain of the current\n> stage instead of gradually increasing the gain value.\n> \n> Depending on the tuning file this leads to very visible oscillations and\n> jumps in the brightness.\n> \n> Fix by clamping the exposure time in the second step to the maximum\n> exposure time of the current stage.\n> \n> While at it, add two comments for easier understanding.\n> \n> Fixes: 34c9ab62827b (\"ipa: libipa: Add ExposureModeHelper\")\n> Signed-off-by: Stefan Klug \n\nReviewed-by: Paul Elder \n\n> ---\n> src/ipa/libipa/exposure_mode_helper.cpp | 4 +++-\n> 1 file changed, 3 insertions(+), 1 deletion(-)\n> \n> diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp\n> index f235316d3539..0c1e99e31a47 100644\n> --- a/src/ipa/libipa/exposure_mode_helper.cpp\n> +++ b/src/ipa/libipa/exposure_mode_helper.cpp\n> @@ -182,6 +182,7 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const\n> \t\t * the stage limits are initialised.\n> \t\t */\n> \n> +\t\t/* Clamp the gain to lastStageGain and regulate exposureTime. */\n> \t\tif (stageExposureTime * lastStageGain >= exposure) {\n> \t\t\texposureTime = clampExposureTime(exposure / clampGain(lastStageGain));\n> \t\t\tgain = clampGain(exposure / exposureTime);\n> @@ -189,8 +190,9 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const\n> \t\t\treturn { exposureTime, gain, exposure / (exposureTime * gain) };\n> \t\t}\n> \n> +\t\t/* Clamp the exposureTime to stageExposureTime and regulate gain. */\n> \t\tif (stageExposureTime * stageGain >= exposure) {\n> -\t\t\texposureTime = clampExposureTime(exposure / clampGain(stageGain));\n> +\t\t\texposureTime = clampExposureTime(stageExposureTime);\n> \t\t\tgain = clampGain(exposure / exposureTime);\n> \n> \t\t\treturn { exposureTime, gain, exposure / (exposureTime * gain) };\n> -- \n> 2.43.0\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id A9459C3259\n\tfor ;\n\tFri, 28 Feb 2025 04:24:24 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id AD62568764;\n\tFri, 28 Feb 2025 05:24:23 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 64154614EB\n\tfor ;\n\tFri, 28 Feb 2025 05:24:21 +0100 (CET)","from pyrite.rasen.tech (unknown\n\t[IPv6:2404:7a81:160:2100:7597:2d2d:d3f:6ef1])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 2D1EE6AF;\n\tFri, 28 Feb 2025 05:22:50 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"Geb0et2k\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1740716572;\n\tbh=Y86VKThrHBKIpInYwCZbO/ycMs6dV9v3ALySCNEJdRk=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=Geb0et2kwfRh7PELeSV9kPAWSUNQXieICakNNY0d92pJkBgsDoAeo7U/+KOXStf04\n\tBBTKbyD3UsCbxRq0YdCfFlMR8OJUkIChdhltDx1c8ecYbrTaBdQ8qL1cd+3N1o1XAC\n\tEuyBS0i+qA9+iiZUSBjHsqWLwV7+i7tfjcyc76YM=","Date":"Fri, 28 Feb 2025 13:24:13 +0900","From":"Paul Elder ","To":"Stefan Klug ","Cc":"libcamera-devel@lists.libcamera.org","Subject":"Re: [PATCH] ipa: libipa: Fix bug in ExposureModeHelper that leads to\n\toscillations in AEGC","Message-ID":"","References":"<20250227195821.3172905-1-stefan.klug@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20250227195821.3172905-1-stefan.klug@ideasonboard.com>","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]